This competing renewal application is for a five year prospective follow-up study of subjects with a prepubertal and early adolescent bipolar disorder phenotype (PEA-BP) and two contrast groups, i.e., attention deficit hyperactivity disorder (ADHD) and community comparison (CC). At baseline there were 268 subjects (93 PEA-BP, 81 ADHD and 94 CC) and at two year follow-up there were 263 subjects (sample retention 98.1 percent). Because most dropouts occur early in follow-up studies, it is anticipated that the sample size will be stable. The PEA-BP phenotype was defined by current DSM-IV mania or hypomania with elation and/or grandiosity as one criterion. The latter ensured that child mania was not diagnosed using only criteria that overlapped with those for ADHD (e.g., irritability, distractibility) and that subjects had at least one of the two cardinal features of mania (i.e., elated mood and/or grandiosity). PEA-BP has been validated by six month stability of mania criteria and mania diagnoses and by diagnostic outcome at the two year follow-up. Findings supported the main study hypothesis in that PEA-BP subjects phenotypically resembled severe late teenage/adult-onset BP (e.g., long episode duration, mixed mania, rapid cycling). In addition, PEA-BP subjects had low recovery and high relapse rates during follow-up. Discrete episodes of either mania or depression with sudden onsets and offsets, similar to modal presentations in late adolescents and adults, were uncommon. Although it might seem intuitive that child-onset mania would be less severe than BP at older ages, this was clearly not the case. What remains to be answered is whether these child mania subjects will go on to resemble modal late-teenage/adult-onset BP or continue to be chronic and mixed/cycling. Addressing this compelling question will provide prognostic information to families and will inform the design of urgently needed prevention and intervention studies.